It probably would have been a good idea to “start from scratch” and completely update the system rather than do everything 1 piece at a time. Automated gates, automated trains, refurbish trains, etc.
If it was my design, I’d build a new “barn” for the Epcot loop and keep those trains isolated and only sent to the roundhouse for major maintenance.
Of course, I’d also expand the system to serve Studios and DAK and then loop back up to TTC. I still think it would be a great long term investment for Disney.